Vehicles which run using electric power supplied from an overhead wire are conventionally known. The electric power (required electric power) required for such vehicles to run varies according to the running environment, such as the gradient of a line. Therefore, the capacity or amount of power consumption of a substation which supplies the electric power to the overhead wire is determined based on the amount of voltage change due to the required electric power.
In addition, when regenerative electric power is generated due to braking in such a vehicle, the regenerative electric power is transmitted to the overhead wire in order to prevent regeneration cancellation. The regenerative electric power transmitted to the overhead wire is collected by the substation. Therefore, a distance at which substations are provided is determined based on the amount of voltage change due to the regenerative electric power.
Therefore, suppression of peak power of the required electric power and the regenerative electric power (peak cut) has been studied in order to lower costs of a transportation system by reducing the number of substations. A method of mounting a rechargeable battery on a vehicle and performing absorption of regenerative electric power and assistance of required electric power has been considered as a method for peak cut of the required electric power and the regenerative electric power.
Further, it is necessary to appropriately manage SOC (state of charge) of the rechargeable battery in order to perform the peak cut appropriately.
Therefore, the peak cut using the rechargeable battery is considered when the required electric power or the regenerative electric power is equal to or more than peak cut power.
Further, a method of performing charging in such a manner that an increasing or decreasing SOC is within an appropriate range of SOC in order to suppress deterioration of a rechargeable battery mounted on a vehicle with no overhead wire is described in Patent Literature 1.
In addition, a method of controlling a SOC of a rechargeable battery mounted on a vehicle with no overhead wire is disclosed in Patent Literature 2.